Many programming languages support dynamic memory allocation, where memory is allocated and deallocated during program execution. This approach alleviates the need to allocate memory upfront during program compilation, when the amount of memory required by the program may not be known. Memory may instead be allocated and de-allocated during program execution based on runtime demands.
Dynamic memory allocation may lead to memory errors if not properly managed. One example of a memory error is referred to as a dangling pointer. This type of memory error occurs when memory space has been freed by an operating system, but pointers to the memory location are not dereferenced by the program. If the program attempts to access the memory location via the dangling pointer, then unpredictable program behavior may result. In some cases, the memory may have been allocated to another program, which may cause the operating system to throw a fault. In other cases, the memory location may contain different data than expected, leading to data corruption.
Memory leaks are another type of error that may occur if memory allocation is not properly managed. This type of memory error occurs when an object that is no longer used by a program is not freed. For example, a program may put an object into a hash table but omit code to properly remove the object. As a result, the object may remain in memory indefinitely during program runtime, wasting memory space. Small memory leaks may not lead to significant problems. However, memory leaks may accumulate over the running life of an application. As the amount of memory that is allocated to a program is finite, large memory leaks may cause significant performance degradation and program crashes.
Some programming languages integrate garbage collection to prevent or mitigate memory errors such as dangling pointers and memory leaks. Garbage collection involves the reclamation of memory occupied by objects that are no longer in use by a program. Garbage collection is often effective at preventing dangling pointers. However, garbage collection generally does not guarantee that a program will not experience memory leaks. The reason is that garbage collectors are typically limited to reclaiming objects that are no longer accessible to the program. Thus, the garbage collector may not remove objects that are still accessible to the program, even if these objects are no longer used. As a result, memory leaks may still cause performance degradation and crashes, even in runtime environments with garbage collection.
The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.